In a breathing system of a conventional anesthesia machine, a carbon dioxide (CO2) absorbent is used to absorb the CO2 exhaled by the patient. During this process, the CO2 absorbent becomes gradually inactive and possibly needs replacement during a surgery or between surgeries by, for example, replacing the container which is filled with the CO2 absorbent, i.e., the carbon dioxide absorbent canister. The process of replacing the CO2 absorbent canister depends, in part, on its installation method. Currently, there are primarily four ways to install the CO2 absorbent canister as described below.
(1) A rotary shaft is provided at the installation position of the CO2 absorbent canister of an anesthesia machine. The CO2 absorbent canister is connected to a breathing circuit by engaging the lip of the CO2 absorbent canister with a structure or mechanism in the anesthesia machine, which corresponding to lip of the CO2 absorbent canister, and rotating the CO2 absorbent canister (during this process a breathing gas bypass valve also can be closed simultaneously). After that the canister is fastened by an elastic lock catch, thereby the assembling is completed. A Europe patent of EP 1712246 published on Oct. 18, 2006 describes such an installation structure.
(2) Two vertical sliding bars are provided at the installation position of the CO2 absorbent canister of an anesthesia machine. A tray plate capable of moving up and down along the sliding bar is disposed at the bottom, beneath which a handle to be used by an operator is provided. The operator uses a cam at the back end of the handle to move the tray plate up and down along the sliding bar. The CO2 absorbent canister is, when installed, placed on the tray plate, and then the installation process is completed by means of movement of the tray plate. When in need, the breathing gas bypass valve can be closed by means of the movement.
(3) At the installation position of the CO2 absorbent canister of an anesthesia machine it is provided with a rotating structure. The operator holds the CO2 absorbent canister for rotatably lifting/lowering it by means of a design corresponding to the canister lip, so as to install/uninstall the CO2 absorbent canister and connect the breathing circuit. Also the breathing gas bypass valve can be opened or closed by means of such a motion. This kind of installation structure is disclosed by a Chinese patent published on Aug. 4, 1999 with a publication No. 2331369Y.
(4) Two left and right installation mechanisms are provided at the installation position of the CO2 absorbent canister of an anesthesia machine. Each installation mechanism has a chute. The CO2 absorbent canister can be pushed into the installation mechanism along said two chutes. The operator may lift the CO2 absorbent canister to bring the left and right installation mechanisms rising. The CO2 absorbent canister is fastened via an elastic lock catch inside the installation mechanisms. At the same time, the breathing gas bypass valve is closed so that the CO2 absorbent canister is installed. Upon the pressing on the elastic lock catch, both the left and right installation mechanisms and the CO2 absorbent canister are lowed, and the breathing gas bypass valve is opened at the same time. Here, the operator can remove the CO2 absorbent canister along the chute so as to replace it.
However, the preceding four solutions all have their own disadvantages:
(1) With respect to the first solution, when installing the CO2 absorbent canister, the operator needs to grip the CO2 absorbent canister and rotate it along the rotary shaft against the elastic force of the elastic lock catch. This is continued until the CO2 absorbent canister is tightly locked. During this process, the operator needs to hold the CO2 absorbent canister all the time to overcome its gravity. If the operator loosens the CO2 absorbent canister when it is not tightly locked, the canister shall fall onto the ground. Therefore, the operability of this installation method is poor.
(2) With respect to the second solution, although it is convenient for the operation, the whole mechanism is very complicated and has a huge size, not presenting a compact structure. Moreover, it is not easy to assemble the two sliding bars, and they are not easy to be produced and maintained.
(3) With respect to the third solution, the operator, when installing and uninstalling the CO2 absorbent canister, needs to closely hold the CO2 absorbent canister all the time to overcome its gravity. Also, there is a risk of the CO2 absorbent canister falling onto the ground when the operator looses his hand without tightly cocked the canister.
(4) With respect to the fourth solution, there are two respective steps of placing the CO2 absorbent canister and connecting the breathing circuit, so that the problem of falling due to the incorrect placement and gravity can be solved. However, the operator needs to lift the CO2 absorbent canister when connecting the breathing circuit, thereby the operation is not very convenient.